-- bubble universe (optimized)
-- by movie vertigo

-- consts
init_scale = 32
init_speed = 0.004
speed_change = 0.0001
scale_mul = 1.01
curve_step = 4
init_curve_count = 252
two_pi = 6.283185307179586
inv_two_pi = 0.1591549430918953
ang1_inc = curve_step * two_pi / 235 * inv_two_pi
ang2_inc = curve_step * inv_two_pi

-- vars
x_offset = 0
y_offset = 0
anim_time = 0
scale = init_scale
speed = init_speed
curve_count = init_curve_count
old_btn3 = false
old_speed = 0

function set_palette()
    local p = {129,1,140,12, 133,131,139,138, 128,130,2,136, 8,9,10}
    for i = 1, 15 do pal(i, p[i], 1) end
end

function _init()
    set_palette()
    camera(-64, -64)
end

function _update60()
    local o_held = btn(4)
    local x_held = btn(5)

    if o_held and x_held then
        if btn(0) then speed += speed_change end
        if btn(1) then speed -= speed_change end
        if btn(2) then
            x_offset = 0 y_offset = 0 anim_time = 0
            scale = init_scale speed = init_speed
            curve_count = init_curve_count
        end
        if btn(3) and not old_btn3 then
            if speed != 0 then
                old_speed = speed
                speed = 0
            else
                speed = old_speed
            end
        end
    elseif o_held then
        if btn(2) then scale *= scale_mul x_offset *= scale_mul y_offset *= scale_mul end
        if btn(3) then scale /= scale_mul x_offset /= scale_mul y_offset /= scale_mul end
        if btn(0) then curve_count = max(0, curve_count - curve_step) end
        if btn(1) then curve_count += curve_step end 
    else
        if btn(0) then x_offset += 1 end
        if btn(1) then x_offset -= 1 end
        if btn(2) then y_offset += 1 end
        if btn(3) then y_offset -= 1 end
    end

    old_btn3 = btn(3)
    anim_time += speed
end

function _draw()
    local cstep = curve_step
    local ccount = curve_count
    local a1inc = ang1_inc
    local a2inc = ang2_inc
    local inv2 = inv_two_pi
    local xoff = x_offset
    local yoff = y_offset
    local sc = scale
    local a1_base = anim_time * inv2
    local a2_base = a1_base
    local _sin = sin
    local _cos = cos
    local _pset = pset
    local _color = color

    cls()

    for i = 0, ccount, cstep do
        local c = 1 + ((i >> 6) % 4) * 4
        local a1s = a1_base
        local a2s = a2_base
        local x = _sin(a1s) + _sin(a2s)
        local y = _cos(a1s) + _cos(a2s)

        -- color 1
        _color(c)
        _pset(y*sc+xoff, x*sc+yoff)
        for j = 2, 8 do
            local a1 = a1s + x * inv2
            local a2 = a2s + y * inv2
            x = _sin(a1) + _sin(a2)
            y = _cos(a1) + _cos(a2)
            _pset(y*sc+xoff, x*sc+yoff)
        end

        -- color 2
        _color(c+1)
        for j = 1, 8 do
            local a1 = a1s + x * inv2
            local a2 = a2s + y * inv2
            x = _sin(a1) + _sin(a2)
            y = _cos(a1) + _cos(a2)
            _pset(y*sc+xoff, x*sc+yoff)
        end

        -- color 3
        _color(c+2)
        for j = 1, 8 do
            local a1 = a1s + x * inv2
            local a2 = a2s + y * inv2
            x = _sin(a1) + _sin(a2)
            y = _cos(a1) + _cos(a2)
            _pset(y*sc+xoff, x*sc+yoff)
        end

        -- color 4
        _color(c+3)
        for j = 1, 8 do
            local a1 = a1s + x * inv2
            local a2 = a2s + y * inv2
            x = _sin(a1) + _sin(a2)
            y = _cos(a1) + _cos(a2)
            _pset(y*sc+xoff, x*sc+yoff)
        end

        a1_base += a1inc
        a2_base += a2inc
    end
end